How come Cassandra column oriented since sstable storing records as rows
Unfortunately, the term column-oriented (or columnar) gets mixed a lot with column family for databases. Apache Cassandra is not a column-oriented database.
Cassandra stores data in column families -- a collection of rows which can contain any columns in a sparse fashion. Storage is sparse since only columns that exist are stored in rows. Rows can have any number of columns unlike tables in relational databases which have a fixed size.
In contrast, column-oriented databases store data by field (instead of rows) and are designed for analytics workloads since performing operations such as aggregation is much faster when the all the field (column) values is easily retrieved from disk. Cassandra doesn't store data in this way at all so there's no relation to this kind of database. Cheers!
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